1. Field of the Invention
The invention relates to a mobile communication device, and in particular relates to a mobile communication device with an internal antenna capable of receiving low-band signals without plugging an external earphone.
2. Description of the Related Art
Design goals for personal mobile communication devices or wireless terminal equipment focus on light weight, thinness, compact profile and good communication quality. Mobile phones, for example, feature small streamlined models with multiple functions and applications, and low cost.
Wireless communication apparatus requires more than one antenna such that multiple communication systems can be integrated and applied. Hence, it becomes a design issue and a critical problem to arrange the antennas in the wireless communication equipment and determine dimensions of antennas. In mobile phones or handsets, GSM systems of 850/900/1800/1900 MHz, WCDMA or CDMA2000 system, Bluetooth system and wireless LAN of 2400 or 5200/5800 MHz may be integrated into a single mobile phone, requiring more than 3 antennas. Fortunately, GSM, WCDMA, CDMA2000, Bluetooth and wireless LAN systems all operate in a frequency band around or above 1 GHz, such that necessary antennas can be configured in the mobile phone with great effort by designing the antennas based on ¼ wavelength antenna.
FIG. 1 shows a wireless communication apparatus with plural wireless communication units (or systems) integrated therein. The wireless communication apparatus 100, for example, a handset or a mobile phone, comprises a transceiver/RF unit 101 for processing communications with a base station, a baseband unit 102, a FM/AM unit 103, a DTV (Digital TV) unit 104, a Bluetooth unit 105, a Wi-Fi unit 106 and GPS unit 107. It is noted that HF, VHF and UHF units, such as the FM/AM unit 103 and DTV unit 104, operate in the frequency band below 1 GHz, therefore requiring antennas with greater length and dimension when using ¼ wavelength antennas. Because the dimension of the antenna for the FM/AM unit 103 or DTV unit 104 is too large to be configured into the handset or mobile phone, manufacturers configure either HF, VHF or UHF antenna outside the housing of the handset, or enlarge dimensions of the handset to enclose large HF, VHF or UHF antenna, hence inevitably degrading elegant profile of the handset (or mobile phone) and increasing production costs.
FIG. 2 shows a conventional handset (or mobile phone) 200 with FM/AM unit 201. External earphone 202, plugged into an earphone jack 203, serves as an antenna for receiving FM/AM signals. FM/AM signals are input to an antenna terminal 204 of the FM/AM unit 201, and the FM/AM unit 201 outputs stereo audio signals Ste_R and Ste_L to the external earphone 202 or speakers Sp_R and Sp_L through amplifiers 205. However, it is inconvenient for users to prepare earphones to listen FM/AM radios. Functions for setting FM/AM alarm clocks and timed recording of FM programs cannot be obtained without plugging the external earphone.